Plus One
by darnedchild
Summary: Molly does a favour for Mycroft, and Sherlock gets it wrong. (Prompt: Mollcroft fake relationship with jealous Sherlock)


**A/N :** Stormflagflying answered my shameless begging for a short fic prompt idea – How about a Mollcroft fake relationship where Sherlock gets jealous? Currently unbeta'd, will make corrections once Lil has a chance to look things over.

 **Plus One**

"Are you sure this is a good idea?" Molly brushed her hand down the bodice of her dress once more. She'd been doing that a lot since she'd (reluctantly) put it on that evening. It was far too expensive for her taste, far too figure hugging, far too _everything_. She never should have let Mycroft's assistant talk her into wearing it.

"Oh, no. It's a horrible idea. One worthy of my brother." Mycroft took a deep breath, the kind that whistled ever so slightly as it was drawn past clenched teeth, and continue. "Still, needs must."

 _And people say Sherlock has no social skills_ , she thought. "Doing you a favour, remember?"

"As if I could forget, Miss Hooper." He smiled down at her; and while it wasn't quite as charming as one of Sherlock's (the sincere ones, not the fake ones he used to try to pass off when he wanted something that first year or two), Molly could see how a person could find the elder Holmes brother attractive. When he wasn't being a complete tosser.

"It's Molly. We go over this every time." She looked at the other guests in their bespoke suits and expensive dresses, and bit back another wave of panic. "I have no idea what to say to any of these people. I still don't get why you were desperate enough to ask me to come with you. Surely you know someone more used to . . . this sort of thing."

He sighed, then signalled to a waiter to bring over his tray of champagne. Mycroft handed a flute to her and waited for the waiter to move on before answering. "I asked you because when a person receives an invitation to an intimate affair _here,_ specifically requesting that you bring a plus one, you bring a plus one."

She wouldn't have called a gathering of that many people 'intimate'; but she couldn't comfortably fit more than six around her dinner table without breaking out the folding chairs from her garden, so she might have been biased.

"Fair enough." Molly sipped her champagne and noted that while Mycroft tilted his flute to his lips, he didn't actually drink any of the bubbly liquid. His eyes continued to scan the room, observing the men and women milling about waiting to be summoned to dinner. "But why didn't you ask the woman you've been seeing?"

Mycroft's eyes widened for a moment before he quickly masked his surprise. Not quick enough, unfortunately for him. Molly had spent far too much time around Sherlock to miss something so out of character for the man standing at her side.

"I'm sorry, I must have misheard you. Surely you haven't been listening to my brother's boorish gossip mongering again."

Molly bit her lower lip to fight back the urge to giggle. Mycroft continued to look offended that she'd dared to even suggest such a thing, and it almost broke her. She had to glance away to keep her composure, and her gaze landed on a woman across the room. A woman who turned to her companion as soon as Molly made eye contact.

"Mycroft, is that her?" Molly inclined her head toward the other woman in what she desperately hoped was a subtle manner. "Is she the one?"

He didn't even need to glance in the direction she'd indicated to know who she was talking about. His eyes closed and Molly thought his neck turned the slightest shade of pink above his shirt collar. He took her champagne flute from her fingers and passed it and his own to a nearby waiter, before urging her away from the others and out of danger of being overheard. "How do you . . . What do you know? Exactly. And, more importantly, how much does Sherlock know?"

"He thinks you've been rather cagey the last two weeks. More so than usual, even for you." She tried to peek around his shoulder to see if the other woman was watching them again, but Mycroft leaned his weight to the side and blocked her view. "He figured out that it must be something personal, because you apparently turned beet red after you got a text the other day and almost looked . . . I believe 'giddy' was the word he used."

"I would never," Mycroft huffed, clearly disgusted at the very thought.

Molly smiled. "I thought he might have been exaggerating for the sake of drama. You know how he is. Yesterday, he even asked if I knew who the mystery woman was. Rather pointedly, actually. As if he thought you and I sat around gossiping about our love lives over brunch every Sunday."

Mycroft's brow furrowed. "Why would he assume you would be privy to that sort of information? Assuming there was anything to be privy to."

She gave him a 'You have got to be kidding' look. "Nice save. I completely fell for that, and am now utterly convinced that you have not been sneaking around like a guilty school boy with that lovely lady across the room."

He flushed again, the earlier pink returning and climbing higher up his neck this time. "Keep your voice down. And not a word to my brother. He'll run off to tell Mummy, and then I'll be inundated with phone calls and surprise visits."

"Oh. My. God." Molly's eyes grew comically wide, and her mouth dropped open. "You really do have a girlfriend!"

"Molly!" He cast a furtive look around to see if anyone was listening.

"Right. Sorry." She cleared her throat and tried again, in a much softer tone. "So, how long as this been going on?"

"I am not having this conversation." His expression was stern for all of a minute, then his shoulders lost their tension and he shifted just enough that they could both see the woman in question. "She's a colleague whom I have, on occasion, met for drinks and dinner. _Not_ my girlfriend."

Mycroft's 'not my girlfriend' looked their direction once more. He nodded his head, and she acknowledged him with a brief upward tilt of her lips.

"So why am I here with you instead of her?" Molly asked.

"As I said, we are colleagues. That . . . complicates matters. Considerably." Mycroft deliberately turned away from the other woman, and froze as his gaze landed on a waiter making his way around the room with a tray of hors d'oeuvres. "He wouldn't dare."

Her eyes followed Mycroft's toward the familiar dark-haired man, who was very clearly not a real waiter.

He stopped in front of Mycroft with a smile that came nowhere near reaching his eyes and offered the tray. "Shrimp puff?"

"Sherlock," Mycroft seethed. "What are you doing here?"

"I never could resist a good party." Sherlock tilted the tray toward Molly.

She helped herself to one. "You resist _every_ party. You even tried to sneak off before Mrs Hudson's birthday do, and we held it in your sitting room."

He yanked the tray out of her reach with a grimace. "I said you could have it at my place, I never agreed to attend."

"Utterly fascinating." Mycroft's tone made it clear that it was, in fact, nothing of the sort. "But why are you here? Now. Where you very clearly should not be."

"I've come to see if Molly is bored to tears yet." Sherlock tsked at his brother. "Really, Mycroft. Who brings someone to a stuffy political dinner for a first date? You're lucky Molly hasn't excused herself and tried to slip out through a powder room window to freedom."

Molly really wished she still had her champagne. Or something a bit stronger. "Pardon?"

The brothers ignored her.

Mycroft pinched the bridge of his nose, as if he had a headache. "You went through Miss Hooper's phone."

"She left it out, and a text from 'Mycroft' popped up; what else would I do?" Sherlock said it as if it were obvious. "Why did you just call her Miss Hooper? That's a bit stuffy, even for you, brother dear."

"Because I respect and appreciate her, which is more than I can say about you, brother mine." Mycroft bit off the last two words. "I promised her an exquisitely prepared meal simply for the honour of her company this evening. When was the last time you even bothered to thank Miss Hooper for the time and energy she devotes to catering to your ridiculous whims? And all for what? A packet of crisps and a set of puppy dog eyes every time you feel the need to take advantage of her good nature."

Sherlock straightened to his full height and—somehow—she found herself holding the tray of hors d'oeuvres. He glared down his nose at Mycroft. " _Molly_ knows I appreciate her. Unlike some people, I don't need to bribe her with food just to get her to spend time with me. And I do not take advantage her." He shrank back ever so slightly, his voice losing some of its harshness. "Not anymore."

Mycroft smirked, and it was nothing like the handsome smile he'd given her earlier in the evening. He opened his mouth to say something, but Molly had had enough.

"I cannot believe you went through my phone, Sherlock," Molly growled through clenched teeth. "I'm not even going to ask how you got past the lock screen because that would be a waste of my breath, but why would you even think it would be acceptable to go through my texts?"

There must have been enough barely leashed menace in her voice to finally register with the other two because they both turned to her with equal expressions of surprise, as if they'd somehow forgotten she was there during their brief battle of wills. She shoved the shrimp puffs back into Sherlock's hands.

"And you." She turned her attention to Mycroft. "I don't care how _complicated_ it is, you march over there—right now—and you talk to her. Get her a drink. Something. Go!"

Mycroft looked as if he wanted to argue. After a moment he silently squared his shoulders, gave her a sharp nod, completely ignored his brother, and did as she'd ordered. Molly watched him cross the room to stand next to his . . . whatever she was.

"Molly-" Sherlock started.

She held up her hand and jerked her head toward the closest exit. "Not another word until we're out of sight. I will not have you embarrassing Mycroft here."

As soon as they were in the hall, Sherlock dumped his tray on a table next to a tastefully lavish arrangement of flowers. He quickly pulled the bowtie around his neck loose and dropped it atop the shrimp puffs, then anxiously tapped his fingers against his outer thighs. "Am I allowed to speak, yet?"

"I should say no and tell you to bugger off." Molly leaned back against the opposite wall and took her weight off one aching foot. She never did like wearing heels that high. "Why did you break into my phone? Why would you follow your brother and I here? And, for God's sake, why couldn't you have stolen a tray of champagne instead of those horrid puff things?"

His mouth tilted up into an unexpected grin, before he quickly sobered. "I told you Mycroft has been acting odd. It was quite obvious that he's become involved with someone; and then he started texting you, and I-I had to know if you were the one."

"The one?" Moly frowned as her mind tried to make the same connection Sherlock's had. Surely he didn't think that she and Mycroft . . . "That's what you meant by 'first date'."

He grimaced, as if the very thought left a bad taste in his mouth.

"You have figured out that the woman I sent him off to talk to is the one he's been seeing the last few weeks, haven't you?" Molly prompted.

"I have now, yes." The way he refused to meet her eyes as he nervously tugged at his cuffs mellowed her earlier anger.

"Sherlock?"

"Hmm?" He continued to fidget for a moment, before tucking his hands behind his back and raising his head and finally, finally looking directly at her.

"Were you jealous?" She bit at her lower lip as she waited for his answer. Molly fully expected him to say she was being silly, and that he'd only come looking for her because there was a case he needed immediate help with (whether he was lying or not). She definitely did not expect him to take a deep breath and hesitantly nod.

"It was different, when you were seeing other men." He ran a hand through his hair, ruffling the curls even more than usual, before fluttering it dismissively. "I knew the others were idiots. No matter how attractive you found them, in the end you would never be happy with a man who couldn't keep up with your intellect."

 _Oh._

"But Mycroft is . . ." Molly trailed off, unsure of where she was planning to go with that thought.

"Mycroft is Mycroft. Smarter than either of us. More than enough to keep you mentally engaged. If anyone would be able to look past his-" Sherlock waved his hand, gesturing toward his face and body. "His everything, it would be you. You put up with all of my faults, after all."

"I do," she agreed. Slowly, Molly pushed away from the wall and closed the small distance between them. "I like Mycroft. But I like you even more."

She reached for his hand and he hesitantly allowed her to take it. "What do you want, Sherlock?"

His answer was immediate and concise. "You."

Sherlock's fingers tightened around hers as he gave her a soft smile. "Come to Baker Street."

Molly answered with a smile of her own. "I'd love to. I'll ask Mycroft to have the car drop me off as soon as we're done here."

He jerked back as if he'd been shocked, dropping her hand in the process. "You're staying? Here? With Mycroft?"

"Of course." She stepped toward him—closing the small distance he'd created between them—and put her hand on his chest, just over his heart. Her pulse sped up when Sherlock put his hand over her own and held it there, even though his face made it clear that he was displeased. "Mycroft asked me for a favour. How silly would I be to give up a chance to have the British government owe me in return? Think of all possibilities."

Sherlock blinked several times, then slowly grinned. "Oh, I always knew you were clever, Molly Hooper."


End file.
